1. Field of the Invention
This invention relates to a self-inhibiting differential gearing comprising a carrier; two output gears disposed substantially co-axially in the carrier; a first set of differential gears engaging one of the output gears; and a second set of differential gears engaging the other output gear, the two sets of differential gears engaging one another at least indirectly (i.e. indirectly or directly). Such a differential gearing will hereinafter be referred to as a differential gearing of the kind specified. In a differential gearing of the kind specified, a frictional self-inhibition of differential rotation of the output gears is produced as a result of forces acting between the output and differential gears producing friction at supporting surfaces of the differential gears.
2. Description of Prior Art
An example of a differential gearing of the kind specified, wherein the differential gears are disposed in axis-parallel relation to the output gears in intersecting recesses in the differential carrier, is disclosed in DE-PS-2206107. The self-inhibition of differential rotation of the output gears is achieved primarily due to friction of the differential gears in their recesses, which occurs as a result of reaction forces as the differential gears attempt to displace themselves in consequence of the tooth forces at their points of engagement with the output gears. The output gears themselves are substantially balanced with respect to such forces, as a result of the symmetrical arrangement of the differential gears circumferentially around the carrier.
Another example of differential gearing of the kind specified is disclosed in WO89/03943, wherein helically toothed worm differential gears engage one another by external straight-toothed portions. Another arrangement is disclosed in WO87/00900, wherein differential gears engage through an intermediate gear with transverse rotational axis. In these examples, the loads on the output gears are balanced.